6 Joseph LeConte—Genesis of Metalliferous Veins. 
into open spaces, an oozing and congelation of a coagulable 
plasma mending the broken parts. For such congelation- 
quiescence, stagnation seems to be a necessary con ition 
The arguments which he urges for this view are mainly two. 
1, That vein-contents both metallic and other, even in the same 
as he thinks demonstrative argument ; and his investigations. 
on this subject are undoubtedly of very great interest and 
evious investigators have also attempted to find the 
value. Pr 
valanble metals widely distributed in the rocks, but with indif.- 
ferent success because the analyses have been mostly undis- 
criminating analyses of the whole rock (bausch-analysen). Dr, 
d 
andberger’s analyses on the contrary have been selective 
e finds. 
analyses of the principal minerals. By this metho 
the valuable metals in notable quantities especially in the more 
basic rocks. Olivine, hornblende, augite and the dark micas 
he finds rich in a great number o metals, while the lighter- 
colored micas, feldspar, quartz and therefore the granites and 
gneisses, he finds poor. He thinks therefore that metals are 
derived mostly from igneous rock especially from the newer 
and more basic, and that veins are often rich when rl inter- 
sect metamorphic rocks only because ed saan are leached 
ptio 
of the former or ane on an sig ACRE of the distinction 
between the two. The view which he apparently takes of the 
ascension theory is an extreme view which allies it with the 
vapor, or sublimation-ascension theory. According to the 
ascension theory, as he imagines it, the water comes up, and the 
materials are derived, from the unknown interior of earth— 
the mineral contents of veins are won derived by leaching, 
from the rocks forming the fissure-walls. The ascension theory 
(if we use this name at all) as properly understood, i. e, the 
m = 
